URIteacherknowledge - Lesson 3 The Impact of Man

Lesson Title: Lesson 3 The impact of man; selective breeding.

State Standards:

Some variation in heritable characteristics exists within every species; some of these characteristics give individuals an advantage over others in surviving and reproducing; and the advantaged offspring, in turn, are more likely than others to survive and reproduce. As a result, the proportion of individuals that have advantageous characteristics will increase. 5F/H3.
Heritable characteristics influence how likely an organism is to survive and reproduce. 5F/H4b

Context of Lesson:

Class time: 1 class periods, 47 min
Classroom: Biology Lab

Students have been introduced to the conditions and mechanisms that have contributed to the the origin of life (lesson 1).
Their backgroud knowledge of evolution has been evoked (lesson 2).
Lesson 3 gives students a hands on activity that exemplifies the process of artificial selection as a prelude to an introduction to the notion of natural selection, as proposed by Charles Darwin.
Students will propose their own hybrid cross of two dog breeds, with the intent of bringing together the best characteristics of the breeds into the F1 generation.
They may become surprised when their classmates get to choose which characteristics are manifested in their resulting cross.
Nature doesn't a;ways do what you expect.

Materials:

Colored stock paper
Worksheet template

BIO CP1 Hybridization Worksheet.doc

Objectives:
Students will demonstrate an understanding of the impact of man on evolution. They will show that evolution takes place in domestic animals at least in part, through the process of selective breeding.

Instruction: Lesson 3
Opening:

Class time	Activity	Description
5 min	Settle in	Meet and greet students at the door of the classroom Take role Return homework from previous day Check homework but do not collect Assume a position in front of the class and ask for the students’ their attention.
5 min	Warm-up /Review	I begin with the question: does anyone have any questions resulting from their 15 minutes of fun? Students may or may not have questions. If they do we engage in discussion. If they do not, then I will ask a question or two to get the conversation started I will limit this warm-up/review to 5 minutes or less
2 min	Question of the day	Have you ever considered crossing your two favorite dog breed’s to see what characteristics might show-up in the hybrid? Well… you in luck because today you get to do just that…on paper of course.

Engagement:

Class time

Activity

Description

20 min

Hybrid cross of two purebred dogs

Students will be given a worksheet (the worksheets are printed on different colored stock paper). They are asked to list five favorable characteristics (both physical & behavioral) for their chosen breeds the instructions are as follows: (link to worksheet)

Selective Breeding aka Artificial Selection (or) An Exercise in Hybridization.
Part 1: Engage in a hypothetical artificial selection process by creating a cross-breed (hybrid). Use the following criteria:* You may only cross within a species, because your goal is to generate offspring that are viable (able to produce future offspring) i.e. all dogs are the same species.

Remember that you are making your cross in order to bring favorable characteristics together and not because the common names sound good together i.e. you may not cross a bulldog with a shiatsu just because you are entertained by the resulting name!
The resulting cross-breed (hybrid) should have some functional or esthetic value. In other words, there should be some good reason for making the proposed cross.
List five desired characteristics for each of your chosen breeds & do not enter the results in the last column, rather when you are finished, put down you pen and wait for further instructions

As the students are working individually, I will walk around the room to assist those in need; keep students on task and answer any questions that may arise.

Part 2: Now that you have listed the desirable characteristics of each of your breeds you should find someone in the room who has the same color paper as yours and trade worksheets.* Now that you have someone else’s breeding pair in hand you should choose which combination of five characteristics will be manifested in the hybrid.

You may choose any combination that you wish. After all you are simulating the process of independent assortment.
When you have completed this task, trade back for your own worksheet.

When the students get their work back I will give them a few minutes to “exam their hybrid puppies” and show them off to their neighbors.
I will then call upon anyone who wishes to share their data with the class to describe the characteristics of each parent in their cross & the characteristics of the hybrid offspring

5 min

Making a connection

I will ask of the class: what other animals or plants can you think of that have been selectively bred in order to isolate and
If necessary, I will steer the conversation to make a connection between dog breeding and the breeding of cattle or corn and other domestically raised livestock

Closure:

Class time	Activity	Description
5 min	Summative class discussion	We will discuss what students expected to happen versus what actually happened in their crosses; leading to the notion that Nature doesn’t always behave exactly the way we expect it should We will also speak to the concept that over many trials we might begin to observe the manifestation of the desired traits that we are intent upon. That ladies and gentlemen is selective breeding in action.
5 min	Lead in to Darwin’s ideas discussion	So far we have talked about evolution as we know it and artificial selection; but we have yet to address natural selection? I will ask a question of the class that I will not answer (for now): What do you know about natural selection? Hands go up; the discussion is on I will conclude by telling the students that before we dig into the concept too deeply we must first know something about the man who gave us the concept. Enter Charlie Darwin; but that discussion is for another day. Maybe as soon as tomorrow. Bell sounds; class ends.
On exiting the class	Homework	Don’t forget your 15 minutes of fun tonight!

Assessment:

Students will be assessed based on their evidence of understanding of selective breeding as evidenced in their hybridization workseet
Assessment criteria will include: